Stevia is by and far the safest sweetener. This fact is now even acknowledged by FDA (though not willingly). If we look at other commercially available sweeteners all have so many side effects that one will not take those sweeteners even once.
FDA has earlier banned Stevia, most probably to benefit chemical sweetener industry lobby, without any solid basis. This was banned on a study which was conducted in such a manner that common table salt will be proved poisonous. Now once there are studies going on Stevia FDA had to acknowledge its safety and hence they decalared it safe. Stevia is the safest sweetener and it can even be considered safer than sugar as well because sugar can create diabetes, which is a deadly disease and also creates obesity and weight gain for normal people, which are sources of so many other ailments and health problems. While stevia has no side effect all other chemical sweet most of theners has many side effect. Higher quantity and long use of Aspertime can even cause cancer as per studies done earlier.

Mild Headache and sleeplessness are common symptoms which are felt by most of the people using commonly preferred sweeteners like Aspertime. Please see the comparison of side effects and benefit of all sweeteners here.